Tool holder

ABSTRACT

A tool holder has a main body and a holding pin onto which a rotary tool having a corresponding holding bore can be placed. At least one channel for transporting coolant or lubricant, the channel leading to the outer circumference of the holding pin, is arranged in the tool holder. In order to enable cooling of the cutting edges of the rotary tool without great production complexity, at least one longitudinal groove for conducting the coolant or lubricant in a longitudinal direction of the holding pin is arranged on the outer circumference of the holding pin.

The invention relates to a tool holder according to the preamble ofclaim 1, and to a tool arrangement according to the preamble of claim11.

A tool holder of the type in question is known from DE 40 19 506 A1. Ithas a main body and a holding pin onto which a rotary tool constructedas a cutting head and having a corresponding holding bore can be placed.A channel for transporting a coolant and/or lubricant and opening at theouter circumference of the holding pin is arranged in the tool holder.The coolant and/or lubricant is then transported to the cutters of thecutting head via a plurality of coolant bores in the cutting head. Therotary tool is mounted by means of a bolt that is screwed at the frontend face of the holding pin into a corresponding centrally arrangedmating thread in the holding pin, thus tensioning the rotary toolagainst the tool holder. In order to conduct coolant and/or lubricant tothe cutting edges of the rotary tool, at least one channel for thecoolant and/or lubricant is arranged in the annular ridge between theinternal thread and the external thread. Particularly for smaller toolholders with smaller diameters of the holding pin, the rigidity andstrength is additionally reduced by these coolant and/or lubricantchannels, and therefore breakage cannot be reliably avoided. Angledbores must be introduced into the holding pin in order to produce thesechannels, which is extremely expensive. Furthermore, the hardening ofthe holding pin, which is usually necessary, is hampered by the smallwall thicknesses in the coolant bore area, since stress cracks caneasily form.

The problem addressed by the invention is that of creating an economicaland easily producible tool holder and a tool arrangement with such atool holder that enables cooling of the cutting edges of the rotary toolwithout great production effort and expense.

This problem is solved by a tool receptacle with the characteristics ofclaim 1 and by a tool arrangement with the characteristics of claim 11.Advantageous configurations of the invention are specified in thesubordinate claims.

The tool holder according to the invention is characterized in that atleast one longitudinal groove for conducting the coolant and/orlubricant in the longitudinal direction of the holding pin to the frontside thereof is formed on the outer circumference of the holding pin.The longitudinal grooves can run parallel to the longitudinal directionof the holding pin, but can also be helical. These longitudinal grooves,preferably formed with a cross section in the shape of a circularsegment, can be produced more easily than is possible for the generallyinclined bores from prior art.

At least one channel preferably opens at the transition of the holdingpin to the main body. This guarantees that the predominant part of theholding pin does not undergo a reduction of cross section, and thereforedoes not lead to weakening through at least one channel.

In order to create a transition for the coolant and/or lubricant that isparticularly low in friction and facilitates flow for the coolant and/orlubricant, the at least one channel preferably opens into a longitudinalgroove.

In a particularly preferred embodiment, a plurality of longitudinalgrooves that are connected by an annular groove running in thecircumferential direction of the holding pin can be formed on the outercircumference of the holding pin. The coolant and/or lubricant can bedistributed by the annular groove. This is particularly advantageous ifthe lubricant is conducted to the grooves with only a few channels andcan then be distributed there. The lower number of channels in turnresults in less weakening of the holding pin. For a transition of thecoolant and/or lubricant that is low in friction and facilitates flow,the at least one channel preferably opens into a longitudinal groove.The annular groove can be arranged continuously or in sections on theouter circumference of the holding pin. The coolant and/or lubricant canbe further distributed proceeding from the annular groove.

The holding pin can have a circumferential centering ridge on the outercircumference. This centering ridge is designed to cooperate in aforce-fitting sealing manner with the rotary tool, so that passage ofthe coolant and/or lubricant at the centering ridge is suppressed.Reliable sealing can be achieved in this way.

To avoid an undesired escape of coolant and/or lubricant, thelongitudinal groove and the annular groove can be arranged between afront, tool-side end face of the holding pin and the centering ridge.This enables reliable sealing between the holding pin and the rotarytool and ensures a flow of coolant and/or lubricant in the direction ofthe tool end face provided with the cutting edges. The front, tool-sideend face of the holding pin is the free side that is inclined towardsthe pluggable rotary tool.

An annular thin-walled intermediate sleeve that at least partiallycovers the longitudinal groove and the annular groove can be arranged onthe holding pin in order to further improve the flow guidance.

The intermediate sleeve can preferably be sealingly connected in aforce-fitting manner to the holding pin so that the coolant and/orlubricant is always conducted to the end face of the holding pin,independently of the rotary tool. This is achieved, for example, bypressing or shrink-fitting the intermediate sleeve onto the holding pin.In addition to the above friction-fit connections, the intermediatesleeve can also be connected permanently or detachably to the toolholder by adhesion, a threaded connection or the like. Steel, brass,aluminum, plastic and the like can be used as material for theintermediate sleeve.

In another preferred embodiment, the intermediate sleeve can have, onthe outer circumference thereof, a centering bead for centering therotary tool. The centering bead deforms elastically during installationof the rotary tool and can thus center the rotary tool as well as havinga damping effect.

In an advantageous embodiment, longitudinal and/or circumferentialgrooves for conducting coolant and/or lubricant can also be provided onthe inner circumference of the intermediate sleeve.

Such intermediate sleeves are easy and economical to produce andtherefore make it possible to form coolant and/or lubricant channels onthe tool holder in a simple manner.

According to the invention a tool arrangement is also claimed, having atool holder of the type described above and a rotary tool that has aholding bore. The invention provides that at least one tool-sidelongitudinal groove for transporting the coolant and/or lubricant in thelongitudinal direction of the rotary tool is formed on the innercircumference of the holding bore. Thereby the flow cross section of thecoolant and/or lubricant is enlarged, without reducing the crosssection, and thus the stability, of the holding pin.

The at least one channel of the tool holder preferably opens into the atleast one tool-side longitudinal channel of the rotary tool. Thisenables a flow-facilitating transport of the coolant and/or lubricant. Alongitudinal groove of the rotary tool can likewise at least partiallyoverlap a tool-side longitudinal or annular groove of the tool holder,whereby the cross section of the flow channels is enlarged, whichlikewise has a flow-facilitating effect. The at least one tool-sidelongitudinal groove can run parallel to the longitudinal direction ofthe rotary tool, but can also be helical.

Additional details and advantages of the invention emerge from thefollowing description of a preferred embodiment with reference to thedrawings. In the drawing:

FIG. 1 shows tool holder according to the invention with a rotary tool,in a longitudinal section;

FIG. 2 shows a detail view of the tool holder with the rotary tool fromFIG. 1;

FIG. 3 shows a perspective view of the tool holder according to theinvention;

FIG. 4 shows a detail view of another embodiment of the tool holder withthe rotary tool in a longitudinal section;

FIG. 5 shows a detail view of another embodiment of the tool holder withthe rotary tool in a longitudinal section;

FIG. 6 shows a detail view of another embodiment of the tool holder withthe rotary tool in a longitudinal section;

FIG. 7 shows another embodiment of the tool holder with the rotary tooland an additional intermediate sleeve; and

FIG. 8 shows a detail view of the intermediate sleeve from FIG. 7.

FIG. 1 shows a tool holder 1, on which a rotary tool 2 is mounted bymeans of a clamping bolt 3. The tool holder 1 consists of a main body 4,at the front, tool-side end of which a holding pin 5 is arranged. Therotary tool 2 is constructed as a cutting head and has a holding bore 6corresponding to the holding pin 5, such that the rotary tool 2 can bepushed onto the tool holder 1 and is retained and centered radially bythe holding pin 5.

At the side of the tool holder 1 facing away from the rotary tool 2,clamping faces in the form of a positive taper lock interface formounting the tool holder 1 in a spindle (not shown) of a machine toolare formed. Coolant and/or lubricant is conducted via a central coolingbore 7 from the spindle to the cutting edges 8 of the cutting head 2.Starting from the central cooling bore 7, channels in the form of radialbores 9 are provided, which open at the outer circumference of theholding pin 5 at the transition of the holding pin 5 into the main body4 of the tool holder 1.

FIG. 2 shows a detail view of another embodiment of the tool holder 1.Proceeding from the radial bores 9, radial longitudinal grooves 10 forfurther conducting the coolant and/or lubricant are provided on theouter circumference of the holding pin 5, so that the coolant and/orlubricant is conducted between the holding pin 5 and the cutting head 2.An annular chamber 11, into which the longitudinal grooves 10 open andfrom which radial supply bores 12 guide the coolant and/or lubricantdirectly to the cutting edges 8 of the cutting heads 2, is providedinside the cutting head 2.

FIG. 3 shows the progression of the longitudinal grooves 10 in aperspective view of the tool holder 1. Like the radial bores 9, thelongitudinal grooves 10 are uniformly distributed across thecircumference of the holding pin 5 and are oriented in the longitudinaldirection of the holding pin 5. The longitudinal grooves 10 are alsoaligned with the outlet of the radial bores 9. For a better distributionof the coolant and/or lubricant, a radially circumferential annulargroove 13 is provided and is arranged directly at the transition of theholding pin 5 into the main body 4. The annular groove 13 allows apressure equalization between the different longitudinal grooves 10 anda uniform distribution of the coolant and/or lubricant to thelongitudinal grooves 10.

Various means for rotationally fixed clamping of the cutting head arealso shown in FIG. 3. The cutting head 2 usually has a radial transversegroove with which retaining elements 14 of the tool holder 1 engage whenthe tool holder 1 is being assembled. The clamping bolt 2, whichtensions the cutting head 3 against the main body of the tool holder 1,is provided for securing the cutting head 2 in the longitudinaldirection. Due to the standardized design of the cutting head 2 with thetransverse groove, additional seals, not shown, can be arranged in theannular groove 13 in order to prevent undesired escape of coolant and/orlubricant via the transverse groove of the cutting head 2 past theretaining elements 14. It is alternatively also possible, however, tointerrupt the annular groove 13 in the region of the retaining elementsin order to prevent an unintended escape of coolant and/or lubricant.

FIG. 4 shows another embodiment of the tool holder, in which the radialbores 9 likewise open into the radial circumference of the holding pin5, but offset from the transition of the holding pin 5 into the mainbody 4. This makes it possible to provide a centering ridge 15 on theouter circumference of the holding pin 5 between the outlet of theradial bores 9 at the outer circumference of the holding pin 5 and thetransition of the holding pin 5 into the main body 4. The centeringridge 15 is formed radially circumferentially and can deformelastically. The centering ridge 15 has an excess dimension in relationto the inside diameter of the holding bore 6 of the cutting head 2, sothat a force-fitting sealing effect results and a passage of coolantand/or lubricant in the direction of the main body 4 is reliablyprevented. The longitudinal grooves 10 and the annular grooves 13 arearranged between the tool-side front end face 16 of the holding pin 5and the centering ridge 15. A good centering of the cutting head 2 onthe tool holder 1 is also achieved by the elastic deformation of thecentering ridge 15.

FIG. 5 presents a detail view of another embodiment of the tool holder.Unlike the embodiment in FIG. 4, the cutting head 2 in this case hastool-side longitudinal grooves 17 in the holding bore 6 that oppose thelongitudinal grooves 10 of the holding pin 5. In sum, this results in anenlarged flow cross section for the coolant and/or lubricant without areduction of the cross section of the holding pin 5. In an embodimentnot shown here, the tool-side longitudinal grooves 17 can be arranged inthe cutting head 2 offset in relation to the longitudinal grooves 10 ofthe holding pin 5. In this case, the coolant and/or lubricant can bedistributed to the tool-side longitudinal grooves 17 through one or moreannular grooves in the cutting head 2 or the holding pin 5, similar tothe annular groove 13 in FIG. 3.

FIG. 6 shows an additional embodiment, in which the holding bore 6 ofthe cutting head 2 has the tool-side longitudinal grooves 17, but unlikethe previous embodiments, there are no longitudinal grooves in theholding pin 5. Thereby the cross sectional area of the holding pin 5 isnot reduced and therefore its strength is not diminished.

FIG. 7 shows an additional embodiment of the tool holder 1 with therotary tool 2. The structure fundamentally corresponds to FIG. 4, butwith the difference that an intermediate sleeve 18 is arranged betweenthe holding pin 5 and the holding bore 6.

The structure of the intermediate sleeve 18 is illustrated in FIG. 8 ina detail view. As in the embodiment shown in FIG. 4, the holding pin 5also has a centering ridge 15. The intermediate sleeve 18 is pushed ontothis centering ridge 15 and seals in a force-fit manner against theholding pin 5 due to slight under-dimension. Longitudinal grooves 20,which are formed opposite from the longitudinal grooves 10 of theholding pin 5, comparably to the embodiment of FIG. 5, are formed in theintermediate sleeve 18. A circumferential annular groove 19 is alsoformed in the intermediate sleeve 18 for better distribution of thecoolant and/or lubricant. To center the rotary tool 2 relative to theintermediate sleeve 18, the sleeve has, on its outer circumference, acentering bead 21 that is elastically deformable and has a dampingeffect, the bead being slightly crushed due to an over-dimension duringassembly with the rotary tool 2.

Even though the specification and the figures consistently refer to acutting head as the rotary tool 2, the invention is not limited thereto.All rotatable rotationally symmetrical machining tools with a holdingbore for placement on a holding pin of a tool holder and which feed acoolant and/or lubricant to the cutting edges are considered a rotarytool within the meaning of the invention. These include milling anddrilling tools in particular.

The intermediate sleeve can be used in conjunction with the holding pinaccording to the invention, but also with already known holding pins. Inthe latter case the sealing effect is secondary and instead theadvantageous damping effect is primary.

1. Tool holder having a main body and a holding pin onto which a rotarytool with a corresponding holding bore can be placed, wherein at leastone channel opening at the outer circumference of the holding pin isarranged for transporting coolant and/or lubricant in the tool holder,wherein at least one longitudinal groove for conducting the coolantand/or lubricant in the longitudinal direction of the holding pin isarranged on the outer circumference of the holding pin.
 2. Tool holderaccording to claim 1, wherein at least one channel opens at thetransition of the holding pin to the main body.
 3. Tool holder accordingto claim 1, wherein at least one channel opens into a longitudinalgroove.
 4. Tool holder according to claim 1, wherein a plurality oflongitudinal grooves are connected by an annular groove running in thecircumferential direction of the holding pin.
 5. Tool holder accordingto claim 4, wherein at least one channel opens into the annular groove.6. Tool holder according to claim 1, wherein the holding pin has acircumferential centering ridge on the outer circumference.
 7. Toolholder according to claim 6, wherein the longitudinal groove and theannular groove are arranged between the front end face of the holdingpin and the centering ridge.
 8. Tool holder according to claim 1,wherein an annular thin-walled intermediate sleeve, which covers thelongitudinal groove and the annular groove at least in part, is arrangedon the holding pin.
 9. Tool holder according to claim 8, wherein theintermediate sleeve is sealingly connected in a force-fitting manner tothe holding pin.
 10. Tool holder according to claim 8, wherein theintermediate sleeve, on the outer circumference thereof, has a centeringbead for centering the rotary tool.
 11. Tool arrangement having a toolholder according to claim 1 and a rotary tool having a holding bore,wherein the holding bore, on the inner circumference thereof, has atleast one tool-side longitudinal groove for conducting coolant and/orlubricant in the longitudinal direction of the rotary tool.
 12. Toolarrangement according to claim 11, wherein at least one channel of thetool holder opens into at least one tool-side groove of the rotary tool.13. Tool arrangement according to claim 11, wherein at least onetool-side groove of the rotary tool overlaps the longitudinal grooveand/or the annular groove of the tool holder at least in part.